FIG. 5 illustrates a conventional type multi-spindle automatic lathe. In this multi-spindle automatic lathe of prior art, a spindle carrier 9 is freely rotatably provided for an indexing operation. The spindle carrier 9 is freely rotatably provided with spindles 12 evenly spaced each other on a common circle around its rotary axis. A workpiece W is held by means of chuck on each of spindles 12 so as to be processed by a tool 14. A spindle 12 in this multi-spindle automatic lathe is rotated by means of motor 1, as typically illustrated in FIG. 4. The rotary output power of the motor 1 is transmitted from an shaft 5 via a belt 7 and a drive transmitting means to a drive shaft 10. Since a gear provided at one end of the drive shaft 10 engages with a gear 13 provided at each of spindles 12, the rotary movement of the drive shaft 10 is transmitted to each of spindles 12.
A typical motor for the motor 1 is illustrated in FIG. 4.
The motor 1 is designed such that a stator 3 with a coil 2 wound therearound is arranged a case 4 so that its output shaft 5 may be pivotably supported on the case 4 in a central space defined by the stator 3, and a rotor 6 is secured around the outer periphery of the output shaft 5 so as to keep a constant distance from the inner surface of the stator 3. This configuration makes it possible to energize the coil 2 and utilize electromagnetic forces, generated under Fleming's left-hand rule as rotary force to rotate the output shaft 5.
In the above described type multi-spindle automatic lathe, long workpieces W are inserted into the hollow sections of the spindles 12, and are fed progressively. And the unprocessed portion of workpieces W extends outwardly from the spindle carrier 9. Since this configuration causes a spatial interference between the motor 1 and workpieces W, the output shaft 5 of the motor 1 cannot be connected directly with the drive shaft 10 of the spindle carrier 9. Thus the motor 1 is spaced a distance apart, from the spindle carrier 9 and a belt 7, a drive transmitting means 8 and the like are used to connect them each other.
As a result, a multi-spindle automatic lathe utilizing the conventional motor 1 has a complicated structure and large dimensions, which brings forth a problem that a large space for installation is required.
The present invention solves such afore-described problems, and thus it is a major object of the present invention to provide a multi-spindle automatic lathe with a simplified and compact construction.